Circuit breaker interlock means



2 Sheets-Sheet 1 0 r we Ta W H .2 1 I i qiljiiwli 3 1 l l H l h H H 0 v JP w Nov. 10, 1959 J. CUORATO E.TAL

CIRCUIT BREAKER INTERLOCK MEANS Nov. 10, 1959 J. J. CUORATO ETAL cmcuxw BREAKER mmocx MEANS 2 Sheets-Sheet 2 Filed Aug. 23, 1957 United States Patent 1,912,533 ein'c'urr BREAKER INTERLOCK MEANS John lj ctmrato, Springfield, and Fred P. "Sims, Phila- 'd'lphi'a, 1a., ass-mm to Circuit Breaker Com- :pany, Philadelphia, Pa., a "corporation of Pennsylvania Application Augns't'23, 1957, Serial No. 679,980 lliClaiins. crem -s Our ,present invention relates to circuit breakers that are-mounted within an enclosure, and more specifically *to interlock means which will prevent opening of the enclosure while the circuit is On and also prevent the circuit breaker from being operated to the' On position while the enclosure is open. f 1

Most circuit breakers include one or more safety interlocks .to protect operating personnel from injury as well as prevent damage to the equipment. For example, a drawout type-circuit breaker is interlocked to prevent withdrawal of the circuit breaker-from its cubicle while under load in order to prevent arcing at the primary contacts. v

One standard type interlock usually included is the door interlock which permits thecubicle door to be opened only when the circuit breaker is Off. Another standard type isa key interlock-which locks the circuit breaker in the Off position to prevent .unauthorizedor accidental closing of the circuit breaker.

qO-ur invention provides an vinterlockmeans which prevents operation of the circuit breaker to the On position while the door of the enclosure therefor is opened. -;In this manner, an inexperienced person will .not be-suhjected to the dangers of exposed live circuits. This rinterlock means :is interconnected with means to prevent opening of the enclosure door while thecircuit breaker is in the On position. I v

The essence of our invention is the provision of a tripping arm which is movable between a first and a second position together with means for maintaining the tripping arm in its second position as long as the enclosure door is open. When the tripping arm is in the second position it is located so as to interfere with the operation of the circuit breaker operating mechanism thus preventing operation of the circuit breaker to On. Typically the tripping arm may be positioned so that movement thereof from thefirst position to the second position will cause the tripping arm to engage the circuit breaker tripper bar and thereby move the tripper bar, against its bias, away from its reset position.

. If the circuit breaker was On while the tripping arm was in the first position, movement of the tripping arm to its second .position will cause the circuit breaker to trip open. As long as the tripping arm remains in its second position the tripper bar can return to its reset position. so that the circuit. breaker cannot be closed.

.The tripping arrnfis operatively connected to the release means 'for the enclosure door latch. {When the release means is operated to unlatch the door,.the tripping arm is automatically moved to its second position thereby insuring that the circuit breaker is Off before thedoor maybe opened. I

Accordingly, aprirnary object of the instant invention is to provide an interlock means fora circuit breaker whereby the circuit breaker may not be operated while the door to the enclosure'therefor is open.

Another object is 'to provide a circuit breaker having interlock means to prevent opening of the circuit breaker 2,912,533 Patented Nov. 10, 1959 ice ' breaker enclosure cover latch, which is operatively connected to trip the circuit breaker when unlatching the door.

A further object is to provide a circuit breaker interlock means including a tripping arm and means .for maintaining the arm in a, second position against --a biasing means urging the arm to a first position when the circuit breaker enclosure door is open. the second position the tripping arm is located so as to interfere with the circuit breaker operating mechanism to thereby prevent operation of the circuit breaker.

A still further object is to provide a drawout type circuit breaker which cannot be operated while the enclosure door is open unless the circuit breaker is moved to its test racking position.

These as well as other objects of the instant invention will become readily apparent after reading the following description of the accompanying drawings in which:

Figure 1 is a perspective view of a drawout type circuit breaker unit wherein our interlock means may be incorporated.

Figure '2 is a plan view of the interlock means.

Figure 3 is a side view of the interlock means with the side of the enclosure removed looking in the direction of arrows 3-3 of Figure 2.

Figure 4 is a front view of the interlock means with the enclosure cover removed looking in the'direction of arrows 4-4 of Figure 2. I v

Figure 1 illustrates a typical drawout type circuit breaker unit 10 wherein our interlock'means may be incorporated. Circuit breaker unit 10 comprises a circuit breaker 11 disposed within enclosure 12 having a front cover 13 hinged at 14, 15. Circuit breaker 1 1 isprovided with rollers (not shown) so that it may readily be rolled out on rail extensions 16, 17 when extensions 16, 17 are folded tothe horizontal. v

External operating handle 19 acting through operating mechanism 20 ,provides a manual control for the three pairs of cooperating contacts 18. The construction and operation of cooperating contacts 18 is completely described in Patent 2,646,749 assigned to the assignee of the instant invention. Operating mechanism '20 is ofa type well known in the art which includes .a tripper bar 21 common to all three phases whereby the automatic tripping of any one phase will cause all phases to trip open. M Our interlock means is illustrated more particularly in Figures 24. Cover latch 23 is pivotally mounted on pin 24 which projects inwardly .from the bottom 22 of enclosure 12. Coiled about pin 24; is. spring 25 with one end thereof bearing against upwardly extending enclosure lip '26 and the other end engaging latch 23 at hole 27 to thereby bias latch 23 counterclockwise (with respect to Figure 2) about pin 24 to a latch position. Cover latch 23 extends through slot 28 in lip 26 so that the tip 29 of latch 23 is positioned to engage bracket 30, secured to cover 13 by fasteners 31, and thereby maintain the cover 13 closed.

Rod assembly 35 includes cover latch release rod 36 having one end 37 which extends through cover opening 38. Coil spring 39, positioned around rod 36, bears against guide bracket 40 and pin 41 projecting from rod 36 thereby urging rod assembly 35 to project outward through opening 38. Stop nut 42 at end 43 0f 'rod 36 limits this outwardmovement. i

Nuts 44 and bolts 45 secure guide bracket -40-=to' partition 46 which extends upwardly from the bottom When in i Y 3 1 surface 22 of enclosure 12. Lip 26 and guide bracket 40 include holes (not shown) for the journaling of rod 36 while, partition 46 provides a hole through which rod 36 and spring 39 may pass.

' Rod assembly 35 also includes member 47 which is bracket 52 which is secured to partition 46. Pin 41. ex-

tends through longitudinal slot 53 in tripping arm 50. Thus the reciprocating movement of rod assembly 35, as rod 36 is depressed and released, will be accompanied by an oscillatory movement of tripping arm 50.

' When rod 36 is depressed tripping arm 50 is rotated clockwise (with respect to Figure 2) so that the offset end 54 of tripping arm 50 now engages extension 55 of tripper bar 21 thereby allowing the circuit breaker opening springs (not shown) to bring about a disengagement of the pairs of cooperating contacts 18 if they should be engaged at this time. Thus it is apparent that cover 13 cannot be moved from the closed to the open position unless circuit breaker 11 is open.

Maintaining rod 60 is provided to retain tripping arm 50 in engagement with tripper bar extension 55 thereby interfering with the circuit breaker operating mechanism 20 to prevent operation of circuit breaker 11 while cover 13 is opened. U-bracket 61, secured to lip 26 in a suitable manner, provides holes (not shown) in each of its arms to journal longitudinal movement of rod 60. Spring 62 is wound around rod 60 and bears against bracket 61 and pin 63 which extends from rod 60 to bias rod 60 to the left with respect to Figure 2.

Crank 64 is pivoted at 65 to bracket 66 secured to lip 26. Pin 67 connects crank 64 to one end of rod 60 so that clockwise rotation of crank 64 with respect to Figgure 2 will cause rod 60 to move to the right against its bias. Counter-clockwise rotation of crank 64 is limited by its abutment against enclosure lip 26.

L-bracket 68 is secured to cover lip 69 and carries cover projection 70 secured thereto in any suitable manner. With cover 13 closed projection 70 is positioned to extend through opening 71 in enclosure lip 26 and engaged the upwardly turned surface 72 of crank 64 to rotate crank 64 to its clockwise position and move rod 60 to the right thereby permitting rod end 37 to fully extend through cover 13.

As rod end 37 moves under the influence of spring 39, rod 36 carries pin 41 which causes tripping arm 50 to rotate counterclockwise to a position where it no longer is in engagement with tripper bar extension 55 so that tripper bar 21 may now return to its reset position and circuit breaker 11 may be operated to On.

When rod tip 37 is depressed to release latch 23 so that cover 13 may be opened, member 80 carried by rod 36 will move to the position indicated in phantom in Figure 2. As cover 13 is pivoted open, spring 62 is free to move rod 60 to the left since cover projection 70 no longer engages crank 64. With rod 60 in its leftmost position it is in blocking relationship with respect to member 80. Now rod 36 is not free to move under the influence of its biasing spring 39 so that tripping arm 50 remains in engagement with tripper bar extension 55 and thereby prevents tripper bar 21 from resetting. In this manner circuit breaker 11 cannot be operated while cover 13 is open.

'With our interlock means it is nevertheless possible to move circuit breaker 11 to its test position where the control circuits may be tested. That is, when circuit breaker 11 is partially withdrawnfrom enclosure 12 to its test position, tripper bar extension 55 is disengaged from tripping arm end 54 so that tripper bar 21 may reset. However, upon returning circuit breaker 11 to the opcrating position within enclosure 12 extension 55 will be engaged by tripping arm 50 thereby automatically tn'p ping circuit breaker 11 if its pairs of cooperating contacts 18 are in engagement and thereafter preventing resetting of tripper bar 21 until such time as cover 13 is closed. With circuit breaker 11 in the test position its primary contacts (not shown) are disconnected so that even though cooperating contacts 18 are engaged there is no danger present to personnel or equipment.

While element-55 is referred to as a tripper bar extension, this element is not necessarily connected directly to tripper bar 21. Instead, element 55 may be any mechanism which, when engaged by tripping arm 50, will hold circuit breaker 11 in the tripped position.

It should be readily apparent that by mounting the interlock components, presently mounted to enclosure 12, so they are carried by circuit breaker 11 it will be impossible to operate circuit breaker 11 when it is in the test position unless the interlock means is defeated by inserting a tool through opening 71 to rotate crank 64 clockwise. Cover piece 93 is secured to bracket 61 and serves to isolate crank 64 thereby preventing accidental release of interlock 60, 47.

Under certain circumstances it may be desirable to open cover 13 while circuit breaker 11 is On. For this purpose, defeater hole 91 is provided in cover 13. Hole 91 is so positioned that a screwdriver or rod may be in serted therethrough to engage cam surface 92 of latch tip 29 to move cover latch 23 clockwise to free cover bracket 30 and permit opening of cover 13. Upon closing cover 13 after latch 23 has been defeated, cover bracket 30 will engage cam surface 92 to rotate cover latch 23 clockwise until tip 29 may again engage cover bracket 30.

Thus we have provided interlock means which will prevent operation of a circuit breaker when the cover for the enclosure therefor is opened. This function is achieved by placing a member in interfering relationship with the circuit breaker operating mechanism when the cover is open. Further, the interlock means prevents the cover from being opened unless the circuit breaker is off. The latter function is accomplished by having the cover latch release operatively engageable with the circuit breaker tripping mechanism.

In the foregoing, we have described our invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of our invention within the scope of the description. herein are obvious. Accordingly, we prefer to be bound not by the specific disclosure herein but only' by the appending claims.

We claim:

1. An interlock means for a drawout type circuit breaker removably mounted in an enclosure having a cover; said circuit breaker including an operating handle, a pair of cooperating contacts and an operating mechanism; said handle being operatively connected to said mechanism for operation of said cooperating contacts; said interlock means being operatively positionable to interfere with said operating mechanism when said cover is open thereby preventing said cooperating contacts from being brought into engagement; said interlock means being positioned independently of said handle.

2. An interlock means for a circuit breaker mounted in an enclosure having a cover; said circuit breaker including a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism and a handle operatively connected to said mechanism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means and when so engaged moving said tr pper means to said tripped position; said interlock again-ass means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened thereby preventing said co operating contacts from being brought into engagement; said interlock means being positioned independently of said handle.

3. An interlock means for a circuit breaker mounted in an enclosure having a cover; said circuit breaker including a pair o'f-cooperating contacts and a tripper means operatively connected thereto; :said circuit breaker also including an operating mechanism and a handle operatively 'connect'edlto said'mech'anism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means and when so engaged moving said tripper means to saidtripped position; said interlock means including a .first means for maintaining said interlock means in engagement with said tripper means when said cover is opened thereby preventing said cooperating contacts from being "brought into engagement; said cover when in a closed position being operatively engaged with said first means thereby permitting'said interlock means to become disengaged fromsaid tripper means; said interlock means being positioned independently of said handle.

4. An interlock means for a circuit breaker mounted in an enclosure having a cover; said circuit breaker including a pair of cooperating contacts and a tripper means 'operati-vely connected thereto; said circuit breaker also including an operating mechanism and a handle operatively connected to said mechanism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating-contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means and when so engaged moving said tripper means to said tripped position; said interlock means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened thereby preventing said cooperating contacts from being brought into engagement; said cover when in a closed position being operatively engaged with said first 'means thereby permitting said interlock means V to become disengaged from said tripper means; cover including an operating mechanism and a handle operatively connected to said mechanism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means and when so engaged moving said triper means to said tripped position; said interlock means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened thereby preventing said cooperating contacts from being brought into engagement; said cover when in a closed position being operatively engaged with said first means thereby permitting said interlock means to become disengaged from said tripper means; cover latch means operatively positioned to engage and thereby maintain said cover in said closed position; said cover lacth means being operatively connected to said interlock I means; said tripper means being engaged by said interloek' means when said latch means 'i'sunlatched;lntchrlease means operatively "engageable with said cover -'la'tch means and operable externally of said cover; said latch release means, when in engagement with said cover latch means, unlatching said cover and simultaneously moving said interlock meansinto engagement with said tripper means; said interlock means being positioned indepen dently of said handle.

6. An interlock means "for a circuit breaker mounted in an enclosure having a cover; said circuit breaker including a pair of cooperating contacts and-a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism and a handle operatively connected to said mechanism for operation of said contacts; said tripper means operable between "a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said inter-lock means including a'cover latch, a -tripping arm and "a maintaining rod; each of said tri ping arm and said maintaining rod biased toward a first position and movable to a second position; said tripping arm when in its said second position being in engagement with said tripper means and when so=engaged moving said tripper means to said tripped position; means operatively;

connected to said tripping arm for moving said tripping arm "to its :said first and second positions; said means being operatively positioned to engage said cover latch and thereby unla'tch said cover when said tripping arm is "in its said second position; said maintaining rod when in its said first position being operatively positioned to block return of said tripping arm to its said first position; said maintaining rod being in its said first position When's'a'id cover is open andin its said second position when said cover is closed; said interlock means being positioned independently of said handle.

7. An interlock means for a circuit breaker mounted in an enclosure having a cover; said circuit breaker ineluding a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism and a handle operative 1y connected to said mechanism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position;

I said interlock means including a cover latch a tripping arm anda maintaining rod; each of said tripping arm and said maintaining rod biased toward a first position and movable'to 'a' second position; said trippingarm when in its said second position being in engagement with said tripper means and when so engaged moving said tripper means to said tripped position; means operatively connected to said tripping arm for moving said tripping arm to its said first and second positions; said means being operatively positioned to engage said cover latch and thereby unlatch said cover when said tripping arm is'in its said second position; said maintaining rod when in its said first position being operatively positioned to block return of said tripping arm to its said first position; said maintaining rod being in its said first position when said cover is open and in its said second position when said cover is closed; a crank connected to one end of said maintaining rod; said cover including a projection operatively engageable with said crank when said cover is 1 closed; said projection when in engagement with said cran-k causing rotation thereof and movement of said maintaining rod to its said second position thereby enabling said tripping arm to return to its said first position where said tripping means can reset; said interlock means being positioned independently of said handle.

8. An interlock means for a circuit breaker mounted in an enclosure having a cover; said circuit breaker including a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism and a handle operatively connected to said mechanism for operation of said conmeans to said tripped position; a depressible rod operatively connected to said tripping arm; said depressible arm extending from said enclosure through an opening in said cover when said cover is closed; said depressible rod having protruding means; said protruding means engaging said cover latch when said depressible rod is depressed to thereby unlatch said cover; said tripping arm being moved to its said second position when said depressible rod is depressed; said maintaining rod when in its said first position being operatively positioned to block said protruding means thereby preventing return of said tripping arm to its said first position; said maintaining rod being in its said first position when said cover is open and in its said second position when said cover 7 is closed; said interlock means being positioned independently of said handle.

9. An interlock means for a drawout type circuit breaker unit; said circuit breaker unit including a circuit breaker and an enclosure having a cover; said circuit breaker being movable between a test and an operating position; said circuit breaker being within the confines of said enclosure when in said operating position and being partially withdrawn when in said test position; said interlock means being secured to said enclosure; said circuit breaker including a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism for operation of said contacts; said handle being mounted independently of said cover; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means when said circuit breaker is in said operating position andzwhen so engaged moving said tripper means to said tripped position; said interlock means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened and said circuit breaker is in said operating-position thereby preventing said cooperating contacts from being brought into engagement; said tripper means being disengaged from said interlock means when said circuit breaker is in said test position; said interlock means being positioned independently of said handle.

.10. An interlock means for a drawout type circuit breaker unit; said circuit breaker unit including a circuit breaker and an enclosure having a cover; said circuit breaker being movable between a test and an operating position; said circuit breaker being within the confines of said enclosure when in said operating position and being partially withdrawn when in said test position; said interlock means being secured to said enclosure; said circuit breaker including a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism for operation of said contacts; said tripper means operable be tween a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means when said circuit breaker is in said operating position and when so engaged moving said tripper means to said ,tripped'position; said interlock means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened and said circuit breaker is in said operating position thereby preventing said cooper ating contacts from being;brought into engagement; said tripper means being disengaged from said interlock means .when said circuit breaker is in said test position; said cover when in a closed position being operatively engaged with said first means thereby permitting said interlock means to become disengaged from said tripper means; said interlock means being positioned independently of said handle.

11. An interlock means for a drawout type circuit breaker unit; said circuit breaker unit including a circuit breaker and an enclosure having a cover; said circuit breaker being movable between a test and an operating position; said circuit breaker being within the confines of said enclosure when in said operating position and being partially withdrawn when in said test position;-said interlock means being secured to said enclosure; said circuit breaker including a pair of cooperating contacts and a tripper means operatively connected thereto; said circuit breaker also including an operating mechanism for operation of said contacts; said tripper means operable between a tripped and a reset position; said cooperating contacts being disengaged when said tripper means is in said tripped position; said interlock means operatively engageable with said tripper means when said circuit breaker is in said operating position and when so engaged moving said tripper means to said tripped position; said interlock means including a first means for maintaining said interlock means in engagement with said tripper means when said cover is opened and said circuit breaker is in said operating position thereby preventing said cooperating contacts. from being brought into engagement; said tripper means being disengaged from said interlock means when said circuit breaker is in said test position; said cover when in a closed position being operatively engaged with said first means thereby permitting said interlock means to become disengaged from said tripper. means; cover latch means operatively positioned to engage and thereby maintain, 'saidcover in said closed position; said cover latch means being operatively connected to said interlock means; said tripper means being engaged by said interlock means when said latch means is unlatched; latch release means operatively engageable with said cover latch means and operable externally of said cover; said latch release means, when in engagement with said cover latch means, unlatching said cover and simultaneously moving said interlock means into engagement with said tripper means; said interlock means be,- ing positioned independently of said handle.

References Cited in the file of thispatent UNITED STATES PATENTS 2,450,705 Williams Oct. 5, 1948 2,595,102 Santangelo Apr. 29, 1952 2,674,666 Stieglitz Apr. 6, 1954 2,768,254 Pifke Oct. 23, 1956 2,777,024 West Jan. 8, 1957 

